This invention relates to a method of attaching a zipper to a garment and, more particularly, the invention is applicable where the garment provides a flap to cover a zipper attached thereto.
Generally, when a zipper is attached to a skirt or trouser, a flap is provided to cover the zipper and is formed by turning and overlapping some portion of garment material. Referring to FIG. 5 and FIG. 6, one conventional method of attaching a zipper to a garment will be explained. Referring to FIG. 5A and FIG. 5B, a zipper F has a slider S and two zipper tapes FT.sub.1, FT.sub.2. The two zipper tapes FT: and FT.sub.2, are connected by a bottom portion FT.sub.12. Referring to FIG. 5B, the flap Wf is formed by turning and overlapping a front cloth W.sub.1 and the flap Wf is placed on the zipper tape FT.sub.1. A front cloth W.sub.2, is turned and overlapped and is placed on the zipper tape FT.sub.2.
Referring to FIG. 6A, the above-mentioned workpiece is placed on a sewing machine table Mt. Referring to FIG. 6B, the flap Wf and the zipper tape FT.sub.1 are stitched. Referring to FIG. 6C, when the stitch line reaches to the bottom FT.sub.12, the sewing machine is stopped in the needle-down position and the workpiece is rotated by 90 degrees in the direction of arrow "a".
Referring to FIG. 6D, the sewing machine is started again such that the bottom FT.sub.12, is sewed to the flap Wf and the sewing machine is stopped in the needle-down position. Then the workpiece is rotated by 90 degrees in the direction of arrow "b" in FIG. 6D. Referring to FIG. 6E, the sewing machine is started again and the workpiece is fed in the direction of the arrow in FIG. 6E until the stitch line reaches the tip-end portion of the front cloth W.sub.2. Referring to FIG. 6F, when the stitch line reaches the end of the front cloth W.sub.2, the sewing machine is stopped and the thread is cut. Thus, the zipper is attached to the garment.
As described above, the operator has to rotate the workpiece at each stitching line corner, so the stitch line S.sub.1 S.sub.2 S.sub.3 is performed by constantly feeding the workpiece forward. Thereby, each stitch line is a so-called "perfect stitch".
Referring to FIG. 7, it is apparent that the stitch pitch forms "perfect stitch" Sp when the workpiece is fed forwardly, and forms "hitch stitch" Sh when the workpiece is fed reversely. The merits of this conventional method are that 21 each stitch line is a "perfect stitch" but the demerits are that the operator has to rotate the workpiece twice. Further, the operator has to stop the needle in the needle-down position when the machine is stopped and such manual work lowers productivity.
Recently, an automatic zipper attaching machine which eliminates the two rotations of the workpiece has been developed, such that the workpiece is set in a frame and is moved in the X-Y direction accordingly. Since the rotation work is eliminated, if the left zipper tape FT.sub.1 is sewed in forward feed, the right zipper tape FT.sub.2 will be sewed in reverse feed. So, in this case, the right side stitch line will be hitch stitched and such a hitch stitched line degrades the quality of stitching work and the commercial value is lowered.
Referring to FIG. 7, when the workpiece W is fed forward, the stitch line will be a perfect stitch Sp, and when the workpiece is fed reverse, the stitch line will be a hitch line Sh. It is generally apparent that hitch stitch appearing on the garment surface degrades its commercial value, so how to automatically attach a zipper without hitch stitch lines and how to conceal hitch stitch lines are problems requiring solution.